Given:
Cost of two donuts and three cookies = $3.30
Cost of five donuts and two cookies = $4.95
To find:
The cost of each donut.
Solution:
Let x be the cost of each donut and y be the cost of each cookie.
Cost of two donuts and three cookies = $3.30
...(i)
Cost of five donuts and two cookies = $4.95
...(ii)
Multiply equation (i) by 2.
...(iii)
Multiply equation (ii) by 3.
...(iv)
Subtracting (iii) from (iv), we get


Divide both sides by 11.


Therefore, the cost of each donut is $0.75.
17/80 = p/100
p = 17/80 * 100
p = 0.2125 * 100
p = 21.25
Your answer is B F(x) * (0.5)^x
at maximum. dt/dh=0
if you differentiate you will get
-32t=-100
t=3.125